One possible plot could be that Naruto and Sasuke, married, are somehow transported to the DxD world. They have to adapt to the new rules and powers there while also dealing with the reactions of the DxD characters to their relationship.
One idea could be that Naruto and Sasuke are transported to the DxD world and they have to learn the new rules and powers there. They might team up with some of the DxD characters to face a common enemy.
Well, Naruto's ability to use chakra and his various jutsu like the Rasengan could be adapted in the High School DxD world in some interesting ways. Maybe his chakra could be seen as a unique form of magic. Sasuke's Sharingan and his ninja skills could also be tweaked. For example, the Sharingan could give him an edge in detecting the movements of devils and angels in that universe. He could use his ninja stealth to his advantage in battles or when sneaking around in the DxD high school setting.
There are likely some out there. You can start by checking popular fanfiction websites like FanFiction.net or Archive of Our Own. Just search for the key terms 'Naruto Sasuke married DxD crossover' and you might find some interesting reads.
In a High School DxD fanfiction, Naruto and Sasuke's relationship could be a mix of old grudges and new alliances. They could start off on the wrong foot, with Sasuke being distrustful of Naruto's overly friendly nature towards everyone in the new high school environment. However, as time goes on, they would realize that they need each other. Naruto could help Sasuke open up more, and Sasuke could provide Naruto with a more strategic view of things. They might also team up against common enemies in the DxD world, like some of the more malicious devils or fallen angels. Their relationship would be a slow - burning one, with lots of ups and downs as they navigate the new world and their own personal growth.
Issei would be a likely ally. He's the main character in Highschool DxD and is always looking for ways to become stronger. Sasuke's combat skills and knowledge could be very appealing to Issei. Also, Rias Gremory could be an ally. As a powerful devil and the leader of her peerage, she would recognize Sasuke's potential and value his skills in battles against common enemies.
In the 'naruto is protected by sasuke fanfiction', Sasuke's protection of Naruto could be multi - faceted. Sasuke, being a powerful ninja, would first of all use his physical strength and speed to block attacks aimed at Naruto. Emotionally, his bond with Naruto would make him extremely vigilant. He might sense Naruto's distress from afar and rush to his aid. In terms of strategy, Sasuke would likely plan their movements carefully when they are in dangerous situations, ensuring Naruto is always in a relatively safe position. His ability to quickly analyze a battle situation and react accordingly would be crucial in protecting Naruto.
Yes, there are such fanfictions in the Naruto fanfiction community. Some fans like to explore unique and creative scenarios in their writing, including this rather unexpected one.
One interesting crossover could be Sasuke in the Highschool DxD world using his Sharingan abilities during Rating Games. His combat skills would add a new dynamic to the battles in the DxD universe.